A handgrip is a kind of exercise equipment used to train muscle strength of a hand or a forearm, and includes one pair of arms and a spring which applies a force in a direction disturbing an approaching motion of the arms.
Using the handgrip, a user repeatedly performs a motion which applies a force and approaches the arms while overcoming the resilient force provided by the spring, and a motion which releases the force and turns the arms to their original positions, thereby increasing the muscle strength of his/her hand or forearm.
There has been disclosed a conventional handgrip which includes one pair of arms and a spring of which both ends are fixed to the right and left arms, respectively, and a center portion is formed in a coil shape. However, since the conventional handgrip has a constant intensity of the resilient force provided by the spring, it is impossible to change strength of the handgrip, i.e., the intensity of the resilient force provided by the spring.
To solve such a disadvantage of the conventional handgrip, in Korean Patent No. 0760083 granted to the applicant of the present invention, there has been disclosed a handgrip capable of controlling the intensity of the resilient force.
The handgrip capable of controlling the intensity of the resilient force includes one pair of first and second arms of which upper portions are rotatably coupled to each other by a rotating shaft, a spring guide having a first guide supported by a pin so as to rotate toward an inside of the first arm and a second guide coupled to the first guide so as to move in a lengthwise direction, and a spring which is disposed between the first and second guides of the spring guide. The second guide is formed so that a position of an end thereof may move up and down in an inside of the second arm, and thus a position of the spring may be changed, and the intensity of the resilient force may be controlled.
The handgrip capable of controlling the intensity of the resilient force, as described above, has an advantage that a user can adjust the intensity of the resilient force in accordance with his/her muscle strength, but also has a disadvantage that it is limited in providing a high intensity for an athlete.
First, since the spring is located between insides of the one pair of arms, there is a limitation in adding a spring or increasing a size of the spring.
Second, the arms are formed of a plastic material using a mold, and, as the strength of the spring is increased, the arms formed of the plastic material may not sufficiently support the resilient force. To solve such disadvantages, a metallic material may be used, but there is another problem that a manufacturing cost is increased.
That is, the metallic material may ensure a sufficient supporting force due to its own strength, even when it has a simple shape, and thus a simple manufacturing method other than a method using the mold, which can reduce a cost, is required.
Due to such disadvantages, the handgrip used for an ordinary person's casual exercise may control the intensity of the resilient force. However, in the case of the handgrip having the high intensity for the athlete, the center portion thereof still includes the coil-shaped spring.
However, since the handgrip having the high intensity may not control the intensity of the resilient force, separate handgrips should be used according to their intensities, and also as a thickness of a spring wire is increased, the right and left arms are not arranged on the same plane, but may be twisted from each other, and thus a grip feeling may be deteriorated.